Leo Stepanovich Demidov, the hero of Tom Rob Smith's sensational debut thriller, Child 44, seems to have stepped out of the pages of a classic by Hammett or Chandler. He's a rugged WWII veteran, a natural athlete capable of chasing down a fugitive with an hour's head start across a snowy landscape. He has secrets (mostly of the family variety, and mostly sublimated) as well as vices (a meth habit he acquired during the war). And he's got a femme at home who could very well prove to be fatale: his wife, Raisa, a schoolteacher who he suspects may be working on more than just lesson plans with one of her colleagues. He's also developing an unwelcome virtue — a sense of conscience — as he stumbles on a series of gruesome murders of young children that local authorities seem incapable of solving on their own.